The present invention is concerned with an apparatus for adjusting biasing forces of such leaf springs.
Such leaf springs have been known and widely used as adapted to exert, at their one ends, a predetermined pressing force onto associated members while the other ends being fixed, as those for example in an armatures of electromagnet relays. The biasing force exerted by those springs inconveniently fluctuates, unfortunately, due to inherent warping of the spring materials or due to change or deviation in the dimensions of machines in which the springs are incorporated, which change or deviation inevitably occurs during manufacturing or assembling. Thus, it has been necessary to correct or adjust the forces of the springs, especially in those machines which require biasing forces of springs strictly regulated to fall within a predetermined range, as for example in electromagnet relays, after the assembling or installation of the machine. This adjustment has required troublesome steps of at first measuring the biasing forces of springs after assembling and then imparting slight plastic deformation repeatedly to those springs exhibiting unacceptably high or low biasing force, through bending by, for example, pincers. The bending has to be repeated, at each time measuring the adjusted force, until the biasing force comes up or down to fall within the predetermined range.
These works conventionally required for adjusting the force are extremely inefficient and are likely to cause damages in the spring when imparting the plastic deformation to the later.